Process of cracking hydrocarbon oil



J.l D. SEGUY Feb. 28, 1939.

PROCESS OF CRAGKING HYD-ROCARBON OIL voriginal :Fired Dec. 27, 1927.

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Patented Feb. 28, 1939 UNITED STATES PATENT OFFICE PROCESS 0F CRACKING HYDROCARBON OIL Ware Application December 27, 1927, Serial No. 242,554 Renewed December 3, 1931 8 Claims.

The invention relates to the treatment of the vapors produced by previous cracking and more particularly to the treatment of vapors produced by liquid-vapor phase cracking process of the well known coil and chamber type.

The advantages and the objects of the invention will appear from the hereinafter filed description, and therefore, need not be here recited in detail. In order to more clearly understand the invention, I have shown the accompanying drawing, which is a diagrammatic view of an apparatus suitable for carrying out the invention, but it is understood that this drawing is diagrammatic and not to scale.

Referring to the drawing, I designates a furnace on which is mounted a heating or cracking coil 2. 'Ihe coil 2 is connected by transfer line 3 having throttle valve 4 to the insulated reaction chamber 5. From the top of the reaction chamber 5, the vapors may pass through vapor line 6, having throttle valve 'I into the lower side of dephlegmator 8. The vapors which are not condensed in the dephlegmator pass out through vapor line 9 to condenser I0 and thence to receiver This receiver has gas release control valve I2 and liquid discharge control valve I3,

The residue is drawn out through the lower part of the chamber 5 by draw-off pipe I4 connected to branch I5 leading to the flash chamber I6. A pressure reducing valve I1 is interposed in the line I5. The line I4 has a throttle valve I8. The residue from the flash chamber I6 is drawn out through pipe I9, having throttle valve 20. The vapors from the flash chamber I6 pass out through pipe 2|, having throttle valve 22a, into a series of serially connected vapor phase cracking chambers 22. I have shown two in the drawing, but more than two can be used, if desired. Chambers 22 have residue draw-offs 23 controlled with throttle valve 24. From the last chamber 22 the vapors pass through pipe 25, having throttle valve 26, into the side of dephlegmator 21. From the top of this dephlegmator, the uncondensed vapors and gases pass through line 28 and condenser coil 29 to receiver 30. This receiver 30 has gas control valve 3| and distillate control valve 32.

To the dephlegmator 2'I may be directly fed through pipe 33 having control valve 34, the raw charging stock, or if desired, the temperature may be controlled by passing the raw charging stock through the closed coil 35, having valves 36 and 3l and in the latter case, the preheated oil fed to the feed pump 38 and main inlet line 39, leading to the coil 2. The reflux condensate (ol. 19e-6o) and the preheated raw oil, if the latter is fed directly into the dephlegmator 21, pass through line 46 and pump 4| and line 42 to the inlet feed pipe 39.

The reflux condensate from the primary dephlegmator 8 may be fed to the line 2| through the pipe 43, having control valve 44, or the reflux from the main dephlegmator 8 may be fed through the line 45, having control valve 46 into the line I5 beyond the reducing valve II. Also, if desired, the dephlegmator 3, condenser It and receiver il may be cut out of the system and the vapors from the chamber 5 pass to the line 2| through branch 4l, having control valve 48.

The arrangement is such that in one method of carrying out the invention, the gasoline vapors and lighter gases will be separated in the dephlegmator 8 from the heavier reflux and then this reflux returned through line 43 to the line 2 I, the valve 44 in such case being used as a pressure reducing valve and the reiiuX flashed into the line 2| at the same pressure as is on the chamber I6. In such case, the valve 'I will be opened and the valves 48 and 46 closed.

Another method in which the invention may be operated would be to close the valves 44 and 48 and use the valve 46 as a pressure reducing valve, whereby the reflux condensate will pass to the chamber I6. This might be desirable where the reflux condensate to flash is particularly heavy, and its heavier fractions will be removed through the line I9 with the residue. Another method of operating the invention would be to close the valves l, 44 and 4B and pass all of the vapors through line 4l, using the valve 48 as a pressure reducing valve.

I have provided means for effectively heating the vapors in chambers 22 by passing the flue gases from furnace I through the flue 49 in which is interposed a fan 5I?, this flue leading to the first chamber 22. The arrangement is such that the flue gases come into direct contact with the vapors and superheat them. It is, of course, desirable to control and, in some Cases, within relatively narrow limits, the temperature in the chambers 22. To this end, I am interposing a cooling coil 5I, having valves 52, in the nue 49 to cool the gases if too hot. If the gases are not hot enough, I provide an auxiliary heater 53, having flue 54 connected, as shown at 55, to the flue 49. The arrangement of this auxiliary heater is such that the gases of combustion may enter flue 49 under the pressure of the balance of the system.

In one method of carrying out the invention,

incondensible gas and extraneous gas may be also introduced into the chambers 22 by means of the line 55, having valves 51. Preferably, this gas may be pre-heated by passing it through the heating coil 58, located in the heater 53 and the gas, introduced under sufficient pressure to enter the chambers 22, may be either inert gas, such as nitrogen or the like, or a hydrogenating gas. such as hydrogen. or carbon dioxide, or steam.

Another method of operating "the"inven't'0nf may be to close the damper 59 in therflue 49 and open the damper 6B in the branch 5l.' In such case, the heated gas introduced through the pipe 5B may be the only means for superheating the vapors in the chambers 22. 1 A

In carrying out either of the aboveltwp last mentioned methods, the chambers 22 may be also externally heated through the furnaces '62.'H

Another method `of carrying out the invention may be to put a catalyst, such as ironfoxide or otherv suitable matterin the chamber 5, or the chambers 22, or in both of them. In all of the various methods above referred to, the oilmay be subjected toa pressure of say 200 lbs. or more inthe coi1w2 and the chamber 5., The pressure in the chamber I6 and the dephlegmator Band the, chambers 22 and the dephlegmator 2 1 and its. associatedparts lmay be substantially lower than the pressure in the coil- -say from `100 lbs. down to atmospheric pressure. Another manner of carrying out each of Vthe foregoing methods would-be to have a pressure of say 350 lbs. on the coil A2 and chamber 5, a pressure ofsay 100` lbs. `on the chamber i6 and dephlegmator 8 (in case the latter is-not cut out of the system) while by regulating the reducing valve 63 on line,2l. from 25lbs. say to `atmosphericpressure may beV maintained. on the chambers 22and dephlegmator 21, or if desired, in the last mentioned case, avacuum maybe maintained in the chambers 22 by connecting a suitable-vacuum pump, not shown, to the receiver 30. m N --In the operation of my process as above-de 4scribed,` the 4vapors are dried *invadvance-lof the vapor phase cracking step by reducing the-pres- -sure thereon pounds Vor more toY an ultimate fvaporphase cracking pressure of a relatively 10W order, such that there obtains Yinthe vapors lto be cracked a 'temperaturee'press'ure relationship in which the temperature is' above the saturation 'point forthe reduced pressure. This preliminary drying of the vapors to be'crack'ed` minimizes carbon'formation in the vapor phase cracking zone. In carrying' out any of the methods above described, the degreeA of cracking in the'lliquidvapor phase part of they system, to-'wi'tfinthecil 2. andcharnber A5, may befindepende'ntly coritrolled relative ton the degree of cracking inthe v aporphase cracking chambers 22. Transfer "temperature in. the @0.1i 2 )may .besar SSOFL,

lmore or less, wh e the temperatureinnthe charn- Persmarbelf .Ff morepr less:

By-subjecting the raporsto. vapor pliasegcrael- `ing in the `chambers .22. withtheggases therein contained in the manner heretoforerdescribed, gasoline containing relatively large' percentages lof vantiknock lcompounds may be formed; Also, other-compounds may 4be..forrned,I-l such., as oxygenated compounds.,MVA In carrying out any method of the above-,described process, it .is l ,desirable -to. have .substan- 'tially complete combustion of the flue gases before they enter the chambers 25 in order to avoid combustion of the hydrocarbon vapors.

I claim as my invention:

l. In processes for converting high boiling point oils into low boiling point oils in which the high boilingpoint oil.is subjected tdpressure distillation in a pressure distillation zone, vapors and unvaporized liquid separately removed from the t may be carbon monoxide..V -pressure distillation zone, the unvaporized liquid introduced while hot into a Zone of lower pressure Vwhereinsubstantialdistillation thereof is eiected v Vby the contained heat of the oil, the improvement `whichcomprisesintroducing to the unva- -porized liquid `oilremoved from the pressure distillation zone prior yto further distillation in said zone of lower pressure a lighter oil of lower temperature than said' removed unvaporized liquid oil, removing vapors from said Zone of lower prese sure, andlsubjecting the same to vapor phase cracking by introducing hot gases into direct contact tlfiee'vvtl'ilV "22 A hydrocarbon oil Vcracking process which comprises heating th'eoil'tocraclin'gI temperature under` pressure and separating 'the same'into vapors and unvaporiZ'ediL'ashhistilling the unvaporiedpildn a fiashing lzone"bypressre reduction," introducing 'to said flashing 'z'one 'to be vaporized" therein a"hydr"ocarbon 'oil 'of' lower boiling point' thar'said' unvapcrized oil, removing from the' hashing zone 'the' 'comining'ledflashed vapors and vapors evolved from the'lower boiling oiland subjecting "the same to a 'gasoline-'produ ing vapor phase cracking voperation by introducing hot gases into direct contact'therewith;'and' con"- d'e'nsing theA resultant' gasolineA- vapors as `'a rproductof'the'procss." 3. The 'prec'ess `of vcracking a'mineralhil charge ing stock which comprises vapori'zing the'oil' u'nde'r` a'substantial lsuperatmospheric pressure, dryingthe'cii-'after it" has 'expanded 'into' vapor' by suddenly reducing the pressure thereon nt less than '50 p'ounds'perv square inch totheeirte'nt re- 'duired'to bring the temperature above the'saturationpoint "for the" reduced' pressure, then heating the oil 'vapors 'under the 'reduced' pressure' 'to a cracking temperature and cracking the vapors, and thenv cooling and`fractioh'ati'ngrthe vapors.

-- 2r. The proress'f Anagging; minerai' en" charg- 'ing'stok which comprises heatrrig'th'u and Ythereby vaporizing it' under4 a" substantial super- 2 atrndsphericpressure, allgwing the mvapors 'tc eifr- Apand beyond the' heating: 'rzorfarid infoving v heavy fractio'na thrifdr'ying 'the' pil vvapors 'bw'y reducing theprfessure thereonn't leser-'than' 50 p 'unds per si'uarel'n'ch bringtlfe tempera "frn f t'li rdld 1 bovetle satulratinfpint D .fesilrllthen-...hihsiii"i1 liar. .sindeharaiueed ers'eefif-e1i91ig .temperaturearid @Galina .awifraiiseatinathe rappre.

5. agressief are@ remmer@ O11 ,-@llarging stckwliih 99m12.111s@ heating the QilA tea, Crackngtemperaiure unile iiigwinaiilreilshza heating uciL-illlfiern a relatirelr high supratrnospheric ,pressure enacting.. rijitatsenaraticn 0f' rapciis in a4 primary vaporizing zone maintainedpnder Wapproximately thesamepressueas .the-heating ,coi1, eie'cting` a ,secondaryseparation .of vapors. in a 'secon'dary zone` .maintained under '.a.. .superatmospheric.pressure-lowerlthanfthat.maintained Lonl thelieating boil, unitingitheyapors .separated .from the oilin` said primary-and secondaryfzones and reducing thepressure.onthecombinedvapors @kine Mieraprsnarld ,then

atleast 50..poundsbelow the pressure-atlzwlfiich i any of the vapors were generated, then subjecting the combined vapors to vapor phase cracking at the reduced pressure and subjecting the vapor phase cracked vapors to fractionation and condensation.

6. A process for cracking mineral oil charging stock which comprises heating the oil to a cracking temperature while maintained under a relatively high superatmospheric pressure, effecting an initial separation of vapors from unvaporized oil under a comparatively high superatmospheric pressure, thereafter effecting a further separation of vapors from unvaporized oil under a relatively lower superatmospheric pressure, reducing the pressure on the vapors at least 50 pounds below the pressure at which any of the vapors were generated, and subjecting the same to a vapor phase cracking treatment, and nally cooling and fractionating the vapor phase cracked vapors.

7. The process of cracking a mineral oil charging stock which comprises vaporizing v the oil under a substantial superatmospheric pressure, drying the oil after it has expanded into vapor by suddenly reducing the pressure thereon not less than 50 pounds per square inch and to a reduced pressure such that the temperature of the vapors is above the saturation point for the reduced pressure, then heating the oil vapors under the reduced pressure to a cracking temperature and cracking the vapors, and then cooling and fractionating the vapors.

8. The process of cracking a mineral oil charging stock which comprises vaporizing the oil under a substantial superatmospheric pressure, drying the oil after it has expanded into vapor by suddenly reducing the pressure thereon not less than 50 pounds per square inch and to a reduced pressure of the relatively low order of 25 pounds per square inch or less whereby to bring the temperature of the vapors above the saturation pointl for the reduced pressure, then heating the oil vapors under the reduced pressure to a cracking temperature and cracking the vapors, and then cooling and fractionating the vapors.

JEAN DELAT'I'RE SEGUY. 

